The present invention relates to a crossing assembly for a railway crossing panel. A railway crossing is employed where one track crosses another.
Typically, railroad crossing components are some of the highest maintenance portions of a railroad track arrangement as they must endure repetitive impact and stress.
In prior art arrangement, relatively large frog castings are used to lift the wheels to a height necessary to allow the wheels of a train to cross a main line rail. When the wheels cross the gap they generate impacts that adversely affect the frog, wheels, and the track structure. Although each of the foregoing designs is workable, an improved design that further reduces the railroad maintenance would be desirable.
In providing for rail crossing, it is important to accommodate several aspects relating to the main line running and the crossing rail line.
In order to allow the train car wheel set to cross over a main line rail, it must be raised to a height to allow it to cross the near main running rail, maintained securely at that height to cross the far main running rail and then securely returned to the base running height along the rail course and without causing excessive repetitive bounce typically experienced in prior crossing arrangements.
Typically this is accomplished by using a frog casting disposed between and on either side of the main line rails. These castings are designed to lift the wheel, direct it through the transition zone over both main line rails, and capture the wheel, allowing it to relax to the established rail elevation. For these purposes, the dual frogs are specially cast and custom machined to provide the required shaping, such as that to provide the required ramping and channeling for support and capture of the wheel tread and flange, to be able to firmly and accurately provide mechanical action under high strain and impact conditions.
It is advantageous to be able to provide this mechanical action with reduced expense and effort associated with the production of relatively expensive multiple castings that require custom machining that are customary in the industry. In this regard, frog castings typically incorporate ramping in the design of the main body casting that require rather complex post-casting machining, and it is beneficial to reduce or eliminate complex ramping within the body of the casting.
It is also best to provide a uniform, unbroken wheel path that distributes load and reduces wheel and frog wear, such as may be accomplished by providing a horizontal or otherwise linearly regular wheel path that is not interrupted by wheel-to-rail interface.
Typically frog casting systems must incorporate all of the required ramping with the length of the casting, which requires relatively larger castings to distribute the ramping length to reduce inertial bounce as the wheel sets pass over the main line rail. This makes typical frog casting systems relatively large and expensive. Accordingly, it would be beneficial to reduce the overall casting size, and thereby reduce the initial cost of frog production while at the same time reducing the cost of attendant repair and maintenance.
One type of frog casting used for crossings is the so-called full flange bearing frog that operates by engaging the flange of each of the wheels in a wheel set and raising the wheel set as the wheels ride on their flanges (rather than on their treads) to a crossing height, and are maintained at that height. This type of system offers several advantages such as the use of the wheel flanges as the weight-bearing portion of the wheel, which are not subject to as much reduction in outer diameter as the tread bearing surface over the lifetime of the wheel, thus presenting a more regular bearing surface to the casting.
One of the problems associated with full flange bearing frog castings is that they must be incorporated into a system where all or substantially all of the crossing is constructed of interlocking castings such that they form intersecting continuous flange ways. Accordingly, these castings are relatively large and expensive as compared to crossing systems that incorporate rails or other tread bearing structures.
In addition, full flange bearing frog castings must endure very high stress and impact, reducing their lifetime. Because the replacement costs of such large castings are very high, it is desirable to provide a casting and overall panel set-up that accommodates long-term wear while lowering overall costs of use in terms of lengthening the operational lifetime of the casting within the panel.
It is also beneficial to provide a crossing system that may be made and installed simply, while also being adapted for prefabrication and installation, and one that is relatively easy to assemble and repair. In this regard, it is desirable to eliminate multiple castings, make their production easier and less expensive, and provide frog panels that are adapted to reduce overall track and crossing wear associated with long term use, and that accommodate changes in wheel geometry as wheel degradation occurs over the wheel's operational life cycle.
The embodiments of the invention described herein address the shortcomings of the prior art.